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10.1 Flexible Cords, Cables and Fixture Wires

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Alaska Journeyman Electrician Study Guide Exam

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1 Chapter 1: Alaska Certificates of Fitness, Law & Exam Logistics

1.1 The Alaska Certificate of Fitness System 1.2 Journeyman Eligibility: 8,000 Hours and How Alaska Counts Them 1.3 Trainee, Residential Wireman, Lineman, Provisional & Reciprocal Certificates 1.4 The Journeyman Examination: Format, Scheduling, Open-Book Rules & Retakes 1.5 Adopted Codes, Fees, Renewal, Inspection & Enforcement

2 Chapter 2: Using the 2020 NEC

2.1 Article 90: Purpose, Scope, Arrangement & Enforcement 2.2 Navigating the Code Book: Structure, Index & Tabbing Strategy 2.3 Article 100 Definitions You Must Know Cold 2.4 Electrical Theory for the Exam: Ohm's Law, Power & Three-Phase

3 Chapter 3: General Requirements — Article 110

3.1 Approval, Listing, Interrupting Rating & Terminations 3.2 Temperature Limitations of Terminations — 110.14(C) 3.3 Working Space, Access, Egress & Illumination — 110.26(A) through (D) 3.4 Dedicated Equipment Space, Guarding & Over-1000-Volt Installations

4 Chapter 4: Conductors and Ampacity — Article 310

4.1 Conductor Types, Insulation Markings & Table 310.16 4.2 Ambient Temperature Correction and Alaska's Cold 4.3 Adjustment for More Than Three Current-Carrying Conductors 4.4 Putting It Together: Full Conductor-Sizing Problems 4.5 Parallel Conductors, Dwelling Service Sizing & Conditions of Use

5 Chapter 5: Wiring Methods and Materials — NEC Chapter 3

5.1 Article 300 General Requirements and Underground Cover 5.2 Thermal Movement: Expansion Fittings and Table 352.44 5.3 Boxes and Enclosures: Box Fill and Pull Box Sizing 5.4 Cable Assemblies: NM, MC, AC, SE, UF and TC 5.5 Raceways: RMC, IMC, EMT, FMC, LFMC, PVC and ENT 5.6 Conduit Fill: Chapter 9 Tables and Annex C 5.7 Cable Trays, Wireways, Busways, Gutters and Surface Raceways

6 Chapter 6: Branch Circuits and Feeders

6.1 Branch-Circuit Ratings, Conductor Sizing & Multiwire Circuits 6.2 Required Outlets and Receptacle Spacing in Dwellings 6.3 GFCI Protection — Article 210.8 6.4 AFCI Protection and Receptacle Requirements 6.5 Feeders and Outside Branch Circuits — Articles 215 and 225 6.6 Grounded Conductor Identification, Switches & Panelboards

7 Chapter 7: Overcurrent Protection — Articles 240 and 242

7.1 Article 240 Fundamentals: Ratings, Locations & Conductor Protection 7.2 Feeder Tap Rules — 240.21(B) 7.3 Transformer Secondary Conductors — 240.21(C) 7.4 Fuses, Circuit Breakers, Series Ratings & Article 242 Surge Protection

8 Chapter 8: Services and Load Calculations

8.1 Service Conductors, Clearances and Service Equipment 8.2 Service Disconnects, the 2020 Rule Change, SPDs and Service GFPE 8.3 Article 220 Part II: General Lighting, Receptacles and Demand Factors 8.4 The Standard Dwelling Calculation — Article 220 Part III 8.5 Optional Dwelling and Multifamily Calculations 8.6 Commercial and Industrial Load Calculations 8.7 Neutral Load Calculations and Harmonics — 220.61

9 Chapter 9: Grounding and Bonding — Article 250

9.1 System Grounding, 250.24 and the Main Bonding Jumper 9.2 The Grounding Electrode System — 250.50 through 250.53 9.3 Grounding Electrode Conductor Sizing and Installation 9.4 Bonding: Services, Metal Piping, Structural Metal and Other Systems 9.5 Equipment Grounding Conductors: Types, Sizing and Continuity 9.6 Separately Derived Systems and Separate Buildings 9.7 Ground-Fault Protection of Equipment and Grounding of Specific Equipment

10 Chapter 10: Equipment for General Use — NEC Chapter 4

10.1 Flexible Cords, Cables and Fixture Wires 10.2 Switches, Receptacles and Industrial Control Panels 10.3 Luminaires, Lampholders and Recessed Installations 10.4 Appliances and Fixed Electric Space Heating 10.5 Deicing, Snow Melting, Pipeline and Vessel Heating 10.6 Motors Part I: Full-Load Current, Conductors and Overload Protection 10.7 Motors Part II: Short-Circuit Protection, Controllers, Disconnects and HVAC

11 Chapter 11: Transformers, Generators and Special Occupancies

11.1 Transformers — Article 450 11.2 Generators, Storage Batteries and Energy Storage Systems 11.3 Hazardous (Classified) Locations — Articles 500 through 506 11.4 Garages, Hangars, Fuel Dispensing, Bulk Storage and Spray Application 11.5 Health Care Facilities — Article 517 11.6 Agricultural Buildings, Manufactured Homes, RV Parks and Marinas 11.7 Assembly, Theaters, Carnivals, Temporary Installations and Pools

12 Chapter 12: Special Equipment, Special Conditions and Exam Strategy

12.1 Signs, Cranes, Elevators, Electric Vehicle Charging and Welders 12.2 Solar Photovoltaic, Interconnection and Stand-Alone Systems 12.3 Wind Electric Systems and Fire Pumps 12.4 Emergency, Legally Required Standby, Optional Standby and COPS 12.5 Class 1, 2 and 3 Circuits, Fire Alarm, Optical Fiber and Communications 12.6 Cold-Climate Practice in Alaska: Code Basis and Engineering Judgment 12.7 Exam-Day Strategy: Navigation, Calculation Workflow and Time Management

10.1 Flexible Cords, Cables and Fixture Wires

Key Takeaways Explain This Topic AI

NEC 400.12 prohibits flexible cord as a substitute for fixed wiring, run through holes in walls or ceilings, run through doorways or windows, attached to building surfaces, concealed by walls or above suspended ceilings, installed in raceways, or where subject to physical damage.

Cord type letters decode systematically: S is extra-hard usage, J indicates junior hard service rated 300 volts, O indicates an oil-resistant jacket, W indicates suitability for outdoor use, and E indicates thermoplastic elastomer.

NEC 400.10 requires flexible cords to be connected to devices and fittings so that tension is not transmitted to joints or terminals.

Table 400.5(A)(1) gives flexible cord ampacities, which differ from Table 310.16 building-wire values and depend on the number of current-carrying conductors in the cord.

NEC 400.7 lists the permitted uses of flexible cords, including pendants, wiring of luminaires, connection of portable equipment, and connection of stationary equipment to facilitate frequent interchange.

Last updated: August 2026

Permitted Uses — 400.7

Flexible cords and flexible cables shall be used only for:

  • Pendants ;
  • Wiring of luminaires ;
  • Connection of portable luminaires, portable and mobile signs, or appliances ;
  • Elevator cables ;
  • Wiring of cranes and hoists ;
  • Connection of utilization equipment to facilitate frequent interchange ;
  • Prevention of the transmission of noise or vibration ;

Appliances where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance and repair , and the appliance is intended or identified for flexible cord connection;

Connection of moving parts;

Where specifically permitted elsewhere in the Code.

400.7(B) requires that where used as permitted in (3), (6), and (8), each flexible cord shall be equipped with an attachment plug and shall be energized from a receptacle outlet or cord connector body.

Uses Not Permitted — 400.12

Unless specifically permitted in 400.10, flexible cords and cables shall not be used for the following:

  • As a substitute for the fixed wiring of a structure;
  • Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors ;
  • Where run through doorways, windows, or similar openings ;

Where attached to building surfaces , with an exception permitting cords to be attached to building surfaces in accordance with 368.56(B) for busway plug-in connections;

Where concealed by walls, floors, or ceilings , or located above suspended or dropped ceilings, with exceptions for specified listed assemblies;

Where installed in raceways , except as otherwise permitted in the Code;

Where subject to physical damage .

Item 2 is the one that catches the most installations. A cord run through a hole in a wall to power a shop tool in the next room is a violation regardless of how neatly it is done.

Decoding Cord Type Letters

  • Letter Meaning
  • S Extra-hard usage, 600 volts
  • SJ Junior hard service, 300 volts
  • SV Vacuum cleaner cord, 300 volts, light duty
  • SP Parallel construction (lamp cord)
  • T Thermoplastic
  • E Thermoplastic elastomer
  • O Oil-resistant outer jacket
  • OO Oil-resistant insulation and jacket
  • W Suitable for outdoor use , weather and water resistant
  • P Parallel construction

So SOOW is extra-hard usage, oil-resistant insulation and jacket, and outdoor rated. SJTW is junior hard service, thermoplastic, outdoor rated at 300 volts. SEOOW is extra-hard usage, thermoplastic elastomer, doubly oil resistant, outdoor rated.

Read the letters in order and the cord tells you what it is. Table 400.4 is the master table of trade names, type letters, size, number of conductors, insulation, braid, and use.

Ampacity — Table 400.5(A)(1)

Flexible cords have their own ampacity table, distinct from Table 310.16 for building wire. Values depend on the number of current-carrying conductors in the cord:

  • Size 2 current-carrying conductors, 60 C 3 current-carrying conductors, 60 C
  • 18 AWG 10 A 7 A
  • 16 AWG 13 A 10 A
  • 14 AWG 18 A 15 A
  • 12 AWG 25 A 20 A
  • 10 AWG 30 A 25 A

Table 400.5(A)(3) provides adjustment factors where more than three current-carrying conductors are present: 4 through 6 conductors at 80 percent, 7 through 9 at 70 percent, and so on, paralleling the raceway adjustment table.

400.5(B) notes that a grounded conductor carrying only unbalanced current from other conductors, as in a three-wire circuit, need not be counted, and an equipment grounding conductor is never counted .

240.5 Protection of Flexible Cords, Flexible Cables, and Fixture Wires. Flexible cord and cable shall be protected against overcurrent by either the branch-circuit overcurrent device or by supplementary overcurrent protection. 240.5(B)(1) permits specific cord sizes on branch circuits: 18 AWG cord and larger on a 20-ampere circuit, and 16 AWG and larger on a 20-ampere circuit, under stated conditions for listed appliances and luminaires.

Strain Relief and Terminations

400.10 Pull at Joints and Terminals. Flexible cords and flexible cables shall be connected to devices and to fittings so that tension is not transmitted to joints or terminals . Suitable means include: knotting the cord; winding with tape; using a fitting designed for that purpose; or other approved means.

400.14 Protection from Damage. Flexible cords and cables shall be protected by bushings or fittings where passing through holes in covers, outlet boxes, or similar enclosures.

400.17 Fixture Wires and Flexible Cords in Show Windows and Show Cases and 400.16 Overcurrent Protection complete the general requirements.

400.36 Uses Not Permitted (Portable Cables Over 600 Volts) and Part III of Article 400 cover portable cables above 600 volts.

Fixture Wires — Article 402

402.3 and Table 402.3 list the types of fixture wire — TFN, TFFN, THHN as fixture wire, SF-2, PF, PAF, and others — with their maximum operating temperature, application, insulation, and outer covering.

402.5 and Table 402.5 give allowable ampacities: 18 AWG at 6 amperes, 16 AWG at 8 amperes, 14 AWG at 17 amperes, 12 AWG at 23 amperes, and 10 AWG at 28 amperes.

402.6 Minimum Size. Fixture wires shall not be smaller than 18 AWG .

402.7 Number of Conductors in Conduit or Tubing. The number of fixture wires permitted in a single conduit or tubing shall not exceed the percentage fill specified in Table 1, Chapter 9.

402.10 Uses Permitted. Fixture wires shall be permitted for installation in luminaires and in similar equipment where enclosed or protected and not subject to bending or twisting in use, or for connecting luminaires to the branch-circuit conductors supplying the luminaires.

402.11 Uses Not Permitted. Fixture wires shall not be used as branch-circuit conductors except as permitted elsewhere in the Code.

402.12 Overcurrent Protection. Overcurrent protection for fixture wires shall be as specified in 240.5 .

Cold-Weather Cord Selection in Alaska

The Code does not set a minimum ambient temperature for cord use; it delegates that to the product listing through 110.3(B) . What matters in practice is that thermoplastic jackets stiffen and crack at low temperature, while thermoset and thermoplastic elastomer jackets stay flexible far colder.

  • Jacket family Typical behavior in extreme cold
  • Thermoplastic (T-family, such as SJTW) Stiffens noticeably; risk of jacket cracking when flexed cold
  • Thermoplastic elastomer (E-family, such as SEOOW) Retains flexibility well below zero
  • Thermoset rubber (S, SO, SOOW) Retains flexibility well below zero

Manufacturers publish minimum installation and flexing temperatures for specific cords, and those published limits are enforceable through 110.3(B) when they are part of the listing or labeling. That is the correct Code basis for a cold-weather cord requirement — Alaska adopts the NEC without technical amendments, so there is no state rule mandating a particular cord type.

Two related Alaska realities worth naming:

Engine block heater cords. Ubiquitous in Interior Alaska. These are cord-and-plug connections to portable equipment, permitted under 400.7(A)(3), and the receptacle they plug into outdoors requires GFCI protection under 210.8(A)(3) for dwellings or 210.8(B)(4) for other occupancies. The dedicated-circuit exception in 210.8(A)(3) applies to snow-melting and deicing equipment under 426.28, not to block heaters.

Temporary construction power. Article 590 governs, and 590.6(A) requires GFCI protection for all 125-volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets used by personnel during construction. Cords on a winter job site take a beating; 400.12(7) prohibits use where subject to physical damage, and a cord frozen into ice and driven over is exactly that condition.